1. Field of the Invention
This invention relates generally to telecommunication call processing for a telephone subscriber and more particularly to a network terminator based arrangement located at a subscriber""s premise for performing call waiting, caller identification, call conferencing, call forwarding and dual digital device communication sharing on one S-bus.
2. Description of Related Art
ISDN is defined by internationally accepted standard digital network user interfaces. The resulting network offers a variety of subscriber access lines capable of supporting services including voice, data, facsimile, and video. There are two International Telegraph and Telephone Consultative Committee (CCITT) recommended standard integrated services digital network interfaces for user access. They include a basic rate interface (BRI) and a primary rate interface (PRI). By integrating these various services on a single transport system means, the subscriber avoids buying multiple services to meet multiple service needs. As a practical consideration a single transport system requires less overhead than providing a discrete access line for each service, and results in a total lower cost of service.
An ISDN Basic Rate Interface (BRI) consists of three channels, referred to as two B channels plus a D channel (2B+D), in which all signals flowing over the external telephone company (telco) lines are carried in a baseband digital form and in a standardized frame format. With this arrangement, the B channels are the basic user channels which carry digital voice, high-speed data, and other functions at a maximum channel rate of 64 kbps. The D channel bit rate in this interface is 16 kbps and may serve two purposes. First, the D channel carries control signalling information to control circuit-switched calls on associated B channels at the user interface. In addition, the D channel may be used for packet switching or low speed telemetry when not carrying signalling information. Accordingly, an ISDN Primary Rate Interface consists of multiple B channels and one 64 kbps D channel having primary rates of either 1544 kbps (23B+D) or 2048 kbps (30B+D).
The BRI may be arranged to provide simultaneous voice and data services in several ways giving users flexibility in configuring their services. A user may use each B channel for voice service, for circuit switched data transport, or for packet switched data services. The D channel can carry packet switched data which interleaves data packets with signaling packets. The BRI may provide a maximum of either two data B channels or one voice B channel and another voice or data channel.
Typically, a single line subscriber premise is wired with two discrete pairs of wires, sometimes referred to as plain old telephone service (POTS). In the POTS configuration, one pair of signal wires provides a communication path between analog terminal equipment and a junction box that interfaces to external telco wiring. Another pair of signal wires provides a second, or spare, path between analog terminal equipment and the external junction box.
Although ISDN networks are widely used in current telecommunication systems, coexistence between analog and digital terminal equipment at a customer premise on a single subscription line has heretofore been impractical. As one solution, discrete digital and analog classes of service to the subscriber premise are provided in order to offer support to both analog and digital devices. Thus when a single line subscriber elects to add ISDN service, a junction box connection that interfaces to external telco wiring typically remains fixed, but internal POTS wiring is either bypassed or elaborately modified in order to provide a communication path for digital ISDN signals if only one pair of pre-existing wires exist.
As an alternative solution, a single line subscriber may elect to convert from an analog to a digital class of service. In that scenario, the subscriber premise is converted to accommodate digital terminal equipment only. In so doing, the subscriber is compelled to scrap pre-existing conventional telephone (POTS) wiring and terminal equipment, which had effectively become useless, in order to maintain a single (digital) class of service.
The desirable solution is disclosed in co-pending, earlier filed U.S. patent application Ser. No. 085,333, filed Jun. 30, 1993 and owned in common with this invention. This application discloses an architecture and apparatus for connecting both analog and digital devices in a subscriber premise to a single subscription line in an ISDN network, using existing POTS wiring in the premises.
A disadvantage to an ISDN subscriber arises from various types of class services (e.g., call forwarding, call waiting, caller ID) which are currently handled by the central office switching system and require the user to pay additional charges for their use. An ISDN network includes an ISDN central office switching system which is connected to communication device(s) located at a subscriber""s premise via the subscriber""s telephone line. A computer is connected to the switching system which transmits to the computer associated messages corresponding to call handling information exchanged between the switching system and the user telephone stations connected thereto.
In operation, various types of class services (e.g., call forwarding, call waiting, caller ID) are handled by the central office switching system by transmitting call handling messages (e.g., SETUP, ALERTING, CONNECT, DISCONNECT) from the switch to the user station and vice-versa. The interface between the switch and the station is typically the basic rate interface (2B+D). Since class services currently require processing by the central office switch, the user incurs an additional charge by the telco for these services.
Another disadvantage to a subscriber arises when a digital class of service is used and more than one digital communication device is connected to a single S-bus at the subscriber""s premise. According to current standards for Layer 1 characteristics of ISDN user-network interfaces (CCITT Recommendation I.430), only one digital communication device can be active during a communication session. For example, in a subscriber premise having at least two digital telephone stations connected to a single S-bus, after a subscriber has picked up a receiver of one of the stations no other receiver can be used to talk on the same phone conversation.
A further disadvantage results from the lack of a basic electronic key telephone service (EKTS) for analog phones. Digital telephones currently operate with EKTS and call appearance call handling (CACH) EKTS standards provided by the ISDN network. The digital EKTS phones have numerous buttons and display lights (or a digital display) to allow a user to perform functions such as call conferencing, call hold/retrieve, etc. and the lights or display are used to indicate to the user that these features have been activated. However, there is no such EKTS facilities used for analog telephones. In addition, since the network terminator described in the ""333 application will couple analog devices to the ISDN network, there is a need to develop a user interface for allowing a user to perform functions such as call conferencing and call hold/retrieve on an analog telephone coupled to ISDN EKTS service.
Accordingly, it is an object of the present invention to provide a subscriber""s premise with a network terminator based arrangement which can utilize the B-channels of an ISDN network to perform call waiting, caller identification, call conferencing, call forwarding and communication sharing on one S-bus with more than one digital communication device. It is a further object of the present invention to provide these call processing functions to digital and/or analog devices at the subscriber""s premise. It is yet a further object of the present invention to provide a user interface for mapping actions performed on an analog telephone into EKTS signals recognized by an ISDN network. It is another object of the present invention to provide a single line communication path between digital and analog devices at a subscriber""s premise and an ISDN network through existing POTS wiring.
The present invention is directed to a network terminator (adapter) based arrangement located at a subscriber""s premise which can be connected to a digital telephone network and can perform various call processing functions without the requirement of intervention from a telco switch. The network adapter includes a processor which can perform digital signal processing functions in accordance with the present invention. The adapter is operatively coupled to the digital network and a communication device at the subscriber""s premise.
One embodiment of the present invention is directed to a call processing method which implements call waiting in the network adapter based arrangement. The method includes the step of establishing a first call on a communication device at the subscriber""s premise on a first communication channel. Next, in response to a determination that a second call is being made to the subscriber""s premise, the adapter will connect the second call on a second communication channel.
If the subscriber""s premise does not include a second communication device coupled to the second communication channel, then after connecting the second call on the second communication channel, the adapter will send a private alerting signal to the user (e.g., beeps). Next, the program will enter a loop whereby the user will have the option to toggle between the first and second calls indefinitely until a disconnect request is made from any of the parties to the call. By connecting the two calls on the two communication channels and toggling between them at the user""s option, the adapter eliminates the need for intervention from the telco switch to perform call waiting.
Another embodiment of the present invention is directed to a call processing method which implements caller identification (ID) in the network adapter based arrangement without the need for a separate caller ID box. The method includes the step of receiving a call SETUP message from a switching system specifying an incoming call to the subscriber""s premise. The call SETUP message contains information on the identity of the number initiating the call. After determining that caller ID is activated at the subscriber""s premise and that the receiver has been picked up, the adapter will extract a first message identifying the call from the call SETUP message. Next, the processor within the adapter will voice synthesize the first message to the receiver such that the subscriber will hear an identifying message. The identifying message can be the number of the incoming caller.
Alternatively, the adapter can be provided with a preprogrammed lookup table having a plurality of numbers each of which having a corresponding name. Before voice synthesizing the identifying number to the receiver the adapter can determine whether the identifying number matches any one of the plurality of numbers in the lookup table. In response to a determination that the identifying number matches any one of the plurality of numbers, the adapter will voice synthesize the name to the receiver. In response to a determination that the identifying number does not match any one of the plurality of numbers, the adapter will voice synthesize the identifying number to the receiver.
After hearing the identifying information (number or name of caller) the subscriber has the option of accepting or rejecting the call. If the user chooses to accept the call, the adapter will connect it to an available communication channel. If the user decides not to receive the call, the adapter will continue to return a ringing signal to the caller and return to an idle state.
A further embodiment of the present invention is directed to a call processing method for conferencing up to three calls from a communication device at the subscriber""s premise using the network adapter based arrangement of the present invention. The method includes the step of establishing a first call on the communication device at the subscriber""s premise on a first communication channel. The next step is to initiate from the communication device a call setup request to establish a second call. After the second call is accepted, the adapter will connect the second call on a second communication channel. Next, the adapter will establish a three way communication path between the communication device and the first and second calls by mixing voice data on said first communication channel with voice data on said second communication channel such that each person can listen to each other.
The voice mixing is performed by the processor within the adapter. The local voice signal of one B-channel (B1) is copied downstream of B1 to the upstream of the other B-channel (B2) while the local voice data signal of B2 is copied downstream of B2 to the upstream of B1. This automatically establishes a three way conference call and allows each of the parties to communicate with each other. This voice mixing of the two B-channels by the processor will continue until a disconnect request is made by any one of the parties to the conference call. By connecting each of the calls to a separate communication channel and voice mixing the two channels, the adapter eliminates the need for the Telco""s switching system to conference the calls.
Another embodiment of the present invention is directed to a call processing method of forwarding a call made to a first communication device at the subscriber""s premise to an alternate destination utilizing the network adapter based arrangement. The method includes the step of receiving at the adapter a message from a switching system specifying an incoming call to the subscriber""s premise. Next, the adapter will initiate a first connection on a first communication channel between the first communication device and a second communication device at the alternate destination. After the first connection is established, the incoming call is connected to the first communication device on a second communication channel.
Next, the processor will establish a communication path between the incoming call and the alternate destination by mixing voice data on the first communication channel with voice data on the second communication channel such that a voice communication path is established by the adapter between the incoming call and the alternate destination. The processor will continue voice mixing until a disconnect request is made from the incoming caller or the alternate destination. The method according to this embodiment removes the Telco switch from performing call forwarding.
In each of the above described embodiments the digital network can be an Integrated Services Digital Network (ISDN) and the first and second communication channels can be ISDN B-channels of a basic rate interface. The communication device at the subscriber""s premise can be either an analog or a digital device.
In another embodiment of the present invention, flash hook and touch tone commands allow a user to perform call hold/retrieve, call waiting and three way call conferencing functions on an analog telephone coupled to an ISDN network via the network terminator of the present invention. In addition, if multiple call appearances are provided by the telco, then up to a six way conference call can be established with the analog phone. Each of these call conferencing functions are performed on one B-channel according to EKTS standards. The analog signals (switch hook and touch tone commands) input by a user to the analog phone are converted to ISDN EKTS signals by a telephone interface within the adapter of the present invention.